1. Field of the Invention
The present invention concerns a damping device for a turbojet engine fan blades.
2. Description of the Prior Art
In turbojet engine fans, the practice of mounting the blade roots with play in the disc groove, despite the presence of a metal block, is known.
When the fan turns at maximum speed, the blade roots are pressed against the upper wall of the disc's groove by centrifugal force. In contrast, at low speed or when the engine stops, when the centrifugal force becomes insufficient to press the blade against the top of the groove, or even when the fan windmills under the effect of the wind, the blades have play in their groove and produce a characteristic rattle. This bearing of the blade roots in the groove may lead to a wearing away of the protective covering, hammering of the disc teeth, and local corrosion, all of which are defects that are harmful to the life of the disc and may require a costly part to be discarded.
A number of procedures have been proposed to remedy this defect which is common to all fans. In particular, an elastic metal plate has been placed under the root of the blades, or the enclosure under the platform between two blades has been filled with a synthetic foam.